The aging U.S. population and the prevalence of musculoskeletal disease are driving efforts to take advantage of the regenerative properties of bone. Mesenchymal stem cells (MSCs) used as direct or indirect agents for regenerative therapies are an attractive approach because of their relative abundance in the body and ease of access. However, their effectiveness for bone regeneration relies on their differentiation state. Manipulation of MSCs towards osteoblastic lineage through surface structural cues has been suggested as an approach to improve clinical outcomes.
Micro- and submicro-structures on the surface of titanium alloy implants for dental and orthopedic applications have been shown to promote MSC differentiation into osteoblasts in the absence of external soluble factors in vitro and to improve osseointegration in vivo. See, e.g., Cochran et al., CLIN. ORAL IMPLANTS RES. 13:144 (2002); Olivares-Navarrete et al., BIOMATERIALS 31:2728 (2010); Wall et al., BONE 45:17 (2009).
Recently, we have developed technology for applying nanotexture to the surface of titanium-based implant devices using a gas/solid reaction at high temperatures. Gittens et al., BIOMATERIALS 32:3395 (2011). Using this method, nanoscale titania features of uniform roughness can be introduced over the entire surface of an implant device without altering the overall micro- and submicro-scale topography of the device. In vitro studies showing that osteoblastic differentiation is enhanced on these nanomodified surfaces, suggest that such in vivo osseointegration may be enhanced as well.
Because prior nanotexturing methods require the use of high temperatures (≧700° C.), which may degrade the mechanical performance of an implant device when placed in specific load-bearing functions, we sought to identify a method of forming microscale and/or nanoscale structures on the surface of implant devices using less heat.